The perforation of petroleum producing wells is realized by lowering into the well various metallic perforating-guns of different lengths, the respective charge carriers of which are charged with shaped charges, connected by joints and fired in a vertical fashion, one after another, resulting in a single unit of joined perforating-guns for the perforation of various zones, in a single lowering.
Each perforating-gun contains a ‘carrier tube’ or a charge carrier in which shaped charges, for use in the petroleum industry, of varying geometries are set. Each of the shaped charges detonate conjointly as the charges are in contact with a detonating cord, formed by a tube or vein containing in its interior an explosive granular with controlled properties, through which the explosion advances initiated by an electronic detonator. The explosion of the detonating cord detonates the shaped charges sympathetically.
Perforating guns are detonated one at a time beginning from the bottom and continuing in an upward fashion. After each detonation, the gun assembly is repositioned vertically in such a way that the lowest gun that remains active is located at the desired depth of perforation.
The detonator of each gun is activated by an electronic signal sent from the surface to the mouth of the well, by way of an electronic cable, the conductor of which is protected by a steel wire-mesh. Despite having but a single conductive wire to carry any electrical tension to the gun assembly, the charge is passed through diodes and polarized after the detonation of the bottom gun, so as to ensure that the electric current only arrives at the desired gun.
To fulfill the operation so briefly described, while simultaneously respecting existing norms for the manipulation of explosives, highly capable operators are required to arm and assemble the guns and the wellhead, stripping the ends of connecting wires and joining them by twisting the exposed portions of the wire together and covering the joint with adhesive electrical tape, resulting in an ‘artisanal’ activity requiring extreme caution. It should be noted that petroleum production and exploration activities are generally located in areas with hostile climatic conditions for the operators; work hours are assigned in accordance to the needs of the operation and may include nighttime and daytime hours, with extreme cold or heat, rain or wind, darkness or sunlight. Hours are controlled by working against the clock and by penalizing setbacks; to that respect, it is absolutely necessary that the strictest safety norms be followed while handling explosive material; all of these factors together contribute to an increased likelihood that operators may commit errors while wiring or assembling the perforating guns to be introduced into the well.
From the above facts, there exists an obvious need to simplify the operation of arming and assembling the perforating gun assembly, in other words, simplification of the mechanical assembly and electrical connections of the gun assembly to establish the required firing sequence. The object of this invention deals with the means to perform the electromechanical connection of the gun assembly.